The next global human flu epidemic may begin with a sick duck in Vietnam’s Mekong River Delta, now the epicenter of a deadly bird flu outbreak. The World Health Organization estimates that the H5N1 virus — which already has jumped species from birds to humans — could kill tens of millions of people worldwide. WIDE ANGLE travels to Vietnam to investigate the threat of a global pandemic, portraying Vietnam’s response to outbreaks in its cities, provinces and villages, where doctors, epidemiologists and veterinarians are battling the virus. As the government tries to contain the disease and educate its people, there is growing evidence that the virus is evolving and already may have begun to spread via human-to-human contact for the first time, dramatically increasing the risk of a worldwide catastrophe.